Research conducted in the Unit on Developmental Biology is aimed towards the elucidation of the molecular mechanisms regulating the development of the central nervous system (CNS). The CNS develops through an orderly series of events that are governed by the genetic program and epigenetic signals. The anteroposterior and dorsoventral axis is determined during gastrulation and early stages of neurogenesis. Subsequent steps involve proliferation of neuronal precursor cells, cell migration, axon outgrowth and the establishment of synaptic connections. The spatial and temporal pattern of these events are characteristic for each neuronal structure. Alterations from the normal genetic program can lead to congenital brain defects or psychiatric disorders. Transgenic and embryonic stem cell technologies are employed to study the interaction between epigenetic signal and the neurogenic program in the development of the central nervous system.